In general, in a clutch unit using engagement elements such as cylindrical rollers or balls, a clutch portion is arranged between an input-side member and an output-side member. Further, in the clutch portion, the engagement elements such as cylindrical rollers or balls are engaged and disengaged with respect to wedge gaps formed between the input-side member and the output-side member, thereby controlling transmission and interruption of the input torque.
The applicant of the present invention has previously proposed a clutch unit incorporated into, for example, an automobile seat-lifter section which vertically adjusts a seat through lever operation. This clutch unit is provided with a lever-side clutch portion for transmitting rotational torque from the input side to the output side and a brake-side clutch portion for transmitting rotational torque from the input side to the output side and interrupting torque reversely input from the output side (see, for example, Patent Literature 1).
FIG. 40 is a longitudinal sectional view of an overall structure of the conventional clutch unit disclosed in Patent Literature 1, FIG. 41 is a sectional view taken along the line D-D of FIG. 40, and FIG. 42 is a sectional view taken along the line E-E of FIG. 40.
As illustrated in FIGS. 40 and 41, a lever-side clutch portion 111 mainly includes a lever-side outer ring 114 serving as an input-side member to which torque is input through lever operation, an inner ring 115 serving as a coupling member for transmitting the torque from the lever-side outer ring 114 to a brake-side clutch portion 112, a plurality of cylindrical rollers 116 serving as engagement elements for controlling transmission and interruption of the torque input from the lever-side outer ring 114 through engagement and disengagement between the lever-side outer ring 114 and the inner ring 115, a retainer 117 for retaining the cylindrical rollers 116 at predetermined circumferential intervals, an inner centering spring 118 serving as a first elastic member which is provided between a brake-side outer ring 123 serving as a stationary-side member restricted in rotation and the retainer 117, for accumulating an elastic force obtained by the torque input from the lever-side outer ring 114 and restoring the retainer 117 to a neutral state with the accumulated elastic force through releasing of the input torque, and an outer centering spring 119 serving as a second elastic member which is provided between the lever-side outer ring 114 and the brake-side outer ring 123, for accumulating an elastic force obtained by the torque input from the lever-side outer ring 114 and restoring the lever-side outer ring 114 to the neutral state with the accumulated elastic force through releasing of the input torque.
Note that, in the figures, reference numeral 113 represents a lever-side side plate fixed to the lever-side outer ring 114 by swaging and constituting the input-side member together with the lever-side outer ring 114, and reference numeral 131 represents a washer mounted to an output shaft 122 through the intermediation of a wave washer 130.
Meanwhile, as illustrated in FIGS. 40 and 42, the brake-side clutch portion 112 mainly includes the brake-side outer ring 123 serving as a stationary-side member restricted in rotation, the inner ring 115 serving as a coupling member to which torque from the lever-side clutch portion 111 is input, and a plurality of pairs of cylindrical rollers 127 serving as engagement elements arranged in wedge gaps 126 between the brake-side outer ring 123 and the output shaft 122, for controlling transmission of torque input from the inner ring 115 and interruption of torque reversely input from the output shaft 122 through engagement and disengagement between the brake-side outer ring 123 and the output shaft 122.
Note that, there is provided a larger diameter portion 115c extending from an axial end portion of the inner ring 115 in a radially outer direction and bending in an axial direction. In order to cause the larger diameter portion 115c to function as a retainer for retaining the cylindrical rollers 127 at predetermined circumferential intervals, pockets 115e for accomodating the cylindrical rollers 127 and plate springs 128 are equiangularly formed. In the figures, reference numerals 124 and 125 respectively represent a cover and a brake-side side plate constituting the stationary-side member together with the brake-side outer ring 123, and the brake-side outer ring 123 and the cover 124 are integrally fixed to each other with the brake-side side plate 125 by swaging. Reference numeral 128 represents a plate spring of, for example, an N-shaped sectional configuration arranged between the cylindrical rollers 127 of each pair, and reference numeral 129 represents a friction ring serving as a braking member mounted to the brake-side side plate 125.